Yeah you have to buy members. It's part of the new "Anti Gold Farming" that RS has going on. They made it so people who either put money on a level 3 can't get it off or people who gold farm to sell for RWT/give to their main can't do so. You can take the account into the wilderness and kill it, and it will drop the money. I had to do this with my account and I was pissed.
Edit: this rule only affects new users since the update, so all existing f2p members are fine. Also, when you buy members you are absolved of this restriction forever; regardless of whether or not you are member. It's like a way of taxing us.